The first aim of this proposal is to develop a series of diagnostic tests for prepubertal major depressive disorder using psychoendocrine, polysomnographic, psychophysiological and biochemical correlates of the disorder which differentiate depressive group from neurotic and normal controls. Most of these correlates will be studied and defined in the context of their circadian biological rhythms. Other correlates will be simply stimulation or suppression tests. This projected work rests on the studies done so far by this group on endocrine and sleep correlates of depression which appear to validate the disorder. We aim at developing tests from these correlates which can be of use to the clinician for difficult differential diagnostic problems and as predictors of relapse at the time of terminating effective antidepressant treatment. Thus, the aim is to establish further diagnostic and therapeutic guidelines for the clinician. A second aim is to carry out a long-term follow-up study of prepubertal depressives and controls to test our hypothesis of continuity of prepubertal, adolescent and adult major affective disorders and to develop prognostic guidelines for clinicians.